A clinical study of 70 patients with hernia hiatus oesophagi (59 sliding hernias, 11 paraoesophageal), of whom 22 had received primary surgery, 33 medical treatment and 15 with no discomfort from the hernia had no primary treatment at all. None of the patients in any of these groups had undergone an operation later. A follow-up examination in 1972-73 was achieved in 43 of the 70 patients (16 of those with surgery, 18 with medical treatment and 9 with no treatment); 6 of the others did not attend the follow-up and 21 had died. Of the 16 operated patients, 8 stated they were free from discomfort and 8 that they had improved (7 of the latter only after additional medical treatment). Of the 18 patients who had received only medical treatment, 8 stated that they were free from discomfort (2 of them not until the medication had been changed), 6 that they had improved, 2 had noted no improvement, and 2 a deterioration even though their medication had been changed. Of the 9 untreated patients, 4 stated that they still had no discomfort and 5 that discomfort had materialised later; subsequent medical treatment had eliminated the discomfort in 2 of the later and produced an improvement in 2 more; the 5th patient had not reacted to medical treatment - the follow-up disclosed an inoperable gastric carcinoma.